cachefiles_write_page(): switch to __kernel_write()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/cachefiles/rdwr.c

@@ -880,7 +880,6 @@ int cachefiles_write_page(struct fscache_storage *op, struct page *page)
 {
 	struct cachefiles_object *object;
 	struct cachefiles_cache *cache;
-	mm_segment_t old_fs;
 	struct file *file;
 	struct path path;
 	loff_t pos, eof;
@@ -914,8 +913,6 @@ int cachefiles_write_page(struct fscache_storage *op, struct page *page)
 	if (IS_ERR(file)) {
 		ret = PTR_ERR(file);
 	} else {
-		ret = -EIO;
-		if (file->f_op->write) {
 		pos = (loff_t) page->index << PAGE_SHIFT;
 
 		/* we mustn't write more data than we have, so we have
@@ -933,17 +930,10 @@ int cachefiles_write_page(struct fscache_storage *op, struct page *page)
 		}
 
 		data = kmap(page);
-			file_start_write(file);
-			old_fs = get_fs();
-			set_fs(KERNEL_DS);
-			ret = file->f_op->write(
-				file, (const void __user *) data, len, &pos);
-			set_fs(old_fs);
+		ret = __kernel_write(file, data, len, &pos);
 		kunmap(page);
-			file_end_write(file);
 		if (ret != len)
 			ret = -EIO;
-		}
 		fput(file);
 	}
 

fs/read_write.c

@@ -513,6 +513,8 @@ ssize_t __kernel_write(struct file *file, const char *buf, size_t count, loff_t
 	return ret;
 }
 
+EXPORT_SYMBOL(__kernel_write);
+
 ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
 {
 	ssize_t ret;